Small electro-magnetic contactor

ABSTRACT

A small electromagnetic contactor of the type that a plurality of contacts are opened and closed by an actuator coupled to a movable plunger of electromagnetic device responsive to energizing and deenergizing of the latter. The yoke of the electromagnetic device to which the plunger is electromagnetically coupled is formed from a plate shape magnetic material so as to extend around the coil and plunger to form substantially a closed magnetic path.

United States Patent [191 Usui et al.

SMALL ELECTRO-MAGNETIC CONTACTOR Inventors: Yoshito Usui; Kenii Shiojima, both of Seto; Toshikatsu Hatakeyama; Norio Sakao, both of Owari Asahi, all of Japan Assignee: Matsushita Electric Works, Ltd.,

Osaka, Japan Filed: Aug. 30, 1971 Appl No.: 175,832

Foreign Application Priority Data Aug. 3!, 1970 Japan 45-76972 Aug. 31, i970 Japan 45-87555 US. Cl 335/131, 335/202, 335/262 Int. Cl. H0111 45/00 Field of Search 335/131, 255, 261, 262,

[ Mar. 26, 1974 [56] References Cited UNITED STATES PATENTS 3,l26,782 3/1964 Fauser 335/255 3,219,78l ll/l965 Miller et al. 335/13] 1,894,429 l/l933 Starr 335/262 3,593,240 7/l97l Garczynski 335/26l Primary Examiner-Harold Broome Attorney, Agent, or Firm--Wolfe, Hubbard, Leydig, Voit & Osann, Ltd. 1

[ 5 7] ABSTRACT A small electromagnetic contactor of the type that a plurality of contacts are opened and closed by an actuator coupled to a movable plunger of electromagnetic device responsive to energizing and deenergizing of the latter. The yoke of the electromagnetic device to which the plunger is electromagnetically coupled is fonned from a plate shape magnetic material so as to extend around the coil and plunger to form substantially a closed magnetic path.

3 Claims, 5 Drawing Figures PATENIED was $914 SHEET 2 OF 4 m 4 w V m W m Z54. wx/ 3%? W WZ g SHEET k []F 4 MW m /.N ////An/U PATENIED M26 1974 SMALL ELECTRO-MAGNETIC CONTACTOR This invention relates to improvements in small electromagnetic contactors.

There has been known such small electromagnetic contactors of the type in which a plunger is attracted by excitation of an exciting coil so as to have movable contact pieces contacted with fixed contact pieces through a turning frame as, for example, the one disclosed in US. Pat. No. 2,794,882. However, such type of electromagnetic contactors have a defect that a sizable magnetic loss accurs between the yoke and the plunger owing to the structural arrangement employed therein.

The present invention has been suggested to eleminate such defect, that is, the problem of magnetic loss between the yoke and the plunger is solved of forming the yoke by bending a single plate of magnetic material.

A principal object of the present invention is, therefore, to provide a small-sixed electromagnetic contactor in which the magnetic loss between the yoke and the plunger is negligibly small.

Another object of the present invention is to provide a small electromagnetic contactor which is free of any undesirable variance in the attracting operation of the plunger caused by remanence in the yoke and which is also easy to assemble.

A further object of the present invention is to provide a small electromagnetic contactor which is so designed as to absorb operating motion of the plunger and, thereby, to minimize vibrations of the electromagnet device, so as to prevent chattering of the contacts.

The present invention shall be explained in detail with reference to the accompanying drawings, in which: I

FIGS. 1 and 2 are perspective views of the lower casing portion of the small electromagnetic contactor according to the present invention, showing the electromagnet device with parts disassembled and the device as assembled being installed in the casing, respectively.

FIG. 3 is a diagram illustrating-assembling steps of the respective parts of the electromagnet device;

FIG. 4 is a perspective view of the upper cover por' tion with certain parts disassembled; and

FIG. 5 is a sectional view of the small electromagnetic contactor according to the present invention.

The small electromagnetic contactor of the present invention essentially comprises an upper cover portion and a lower cased portion which are integrally combined as stacked on each other.

FIG. 1 shows, in a perspective view, the parts that constitute the lower cased portion. In the drawing, 1 is a plunger composed of a plurality of laminated iron core plates which are integrally fastened together by means of rivets 2. At the head of the plunger is formed a hole 3, through which a connecting pin 5 is inserted. 4 is a short-circuiting ring, 6 is a coil, 7 is a bobbin which has a hollow space 8 formed centrally therein, in which the plunger 1 is fitted, 9 is a recess provided at each of opposed edges of a flange 10 of said bobbin so as to receive therein respective cushion members 14 to be described later, 11 and 12 are insulating films, and 13 is a lead of the coil 6. The cushion members 14 are made of rubber, soft synthetic resin or the like and each of which has at one side thereofa recess 15 adapted to fit with an edge ofa first side plate of a yoke 17. 16 is a pair of plastic films.

Designated generally by numeral 17 is a yoke, which is formed by bending substantially in U shape a single piece of magnetic material plate, and comprises a top plate 18, a bottom plate 19, the first side plate 20 and two second side plates 21 and 22. Said second side plates 21 and 22 are bent outwardly at the central parts to form lugs 23 and 24. The plunger 1 can move slidingly between said lugs 23 and 24. 25 is an opening formed at one side of said second side plates. The end portions of said second side plates, at the side opposite to said opening, are joined together by welding or other means, as indicated by a joint line 26.

27 designates generally a turning frame made of a plastics and provided with arms 29 and 30 extending from both sides of body portion 28. Respective ends of said arms 29 and 30 terminate in hooks 31, 32, and lobes 33, 34 are provided on both external sides of the arms 29 and 30 as shown.

Referring next to FIG. 2, 35 is a case made of a plastics in a box shape, which having at its top an opening 36. Inside the side walls of said case 35, there are provided cut-out grooves 37, which formed to have at their bottoms substantially semi-circular recesses 38 adapted to receive therein the lobes 33, 34 of the turning frame 27 rotatably. 39 shows a step provided at both side surfaces of the case for mounting thereto a separate mounting fixture (not shown) of the device.

Now, the process of assembling the parts of the electromagnet device will be described. As shown in FIG. 3, the plunger 1 is inserted into the hollow space 8 in the bobbin 7 of synthetic resin, around which the coil is preliminarily wound, and then the insulating films 11, 12 are inserted so as to interpose between the plunger 1 and the walles of said hollow space 8 of the bobbin. Thereafter, the connecting pin 5 is inserted into the hole 3 in the plunger 1 and the bobbin 7 is fitted over the yoke 17 from the side of its opening 25. Insulating films 16 are also fitted between the coil and the top plate 18 and bottom plate 19 of the yoke, respectively. Finally, the cushion members 14 are mounted in such a manner that their recesses 15 fit over the corresponding edges of the first side plate 20 of the yoke. In this case, each of said cushion members 14 is fitted at one side in the corresponding recess 9 in the flange 10 of the bobbin 7. Thus assembled unit of the electromagnet device is shown in FIG. 2, as indicated by 40. This assembly 40 is inserted into the case 35 through its top opening 36 and, then, the turning frame 27 is also fitted into the case so that the lobes 33, 34 of said frame 27 are inserted along the cut-out grooves 37 in the inner walls of the case and finally rotatably fitted in the semi circular recesses 38 and the hooks 31, 32 of said turning frame 27 will engage the connecting pin 5.

FIG. 4 shows top cover portion 41 of the contactor in perspective view, with its principal parts disassembled. In the drawing, 42 denotes a casing, 43 are the partition walls, each of which ia associated with a fixed contact piece 44 provided adjacent thereto. 44 is an opening formed in an end wall of the casing, 46 are outer terminals of said fixed contact pieces 44. 47 is an actuating bar made of synthetic resin and provided with a protuberance 48 at the bottom. Said actuating bar 47 is also provided with several windows 49, in each of which a movable contact piece 50 is fitted and always pressed downwardly in the window 49 by a spring. 51 is a spring which is half inserted in a recess formed at the bottom of the actuating bar. Said actuating bar 4'7 is fitted in a space defined by theopening 45 and partition walls 43 in the casing 42. In the normal fitted condition, the movable contact pieces 50 are positioned in opposition to the corresponding fixed contact pieces 44 but are pushed up by the spring Sll resting on an inner wall opposite to the opening 45 of the casing, so that the movable and fixed contact pieces will be in their OFF state relative to each other. The upper cover portion thus assembled is then fitted over the opening 36 in the lower cased portion. The protuberance 48 of the actuating bar 47 is contacted with the body portion 28 of the turning frame 27 so as to keep the plunger l in a raised-up state. This situation is shown in FIG. 5.

Now, the operation of the electromagnetic contactor of the present invention will be discussed. H6. 5 shows a condition where the plunger 1 is not attracted, that is, the contacts are in OFF state. Under this condition, if the coil 6 is excited, the plunger 1 is attracted to move in the direction of arrow X, causing the turning frame 27 to turn about its pivot 34 so that its body portion pushes the protuberance 48 of the actuating bar 47 in the direction of arrow Y, urging the movable contact pieces 50 to move also in the direction of arrow Y-until they contact the corresponding fixed contact pieces to establish the ON state.

When the coil 6 is disenergized, the actuating bar 47 is urged to move in the direction opposite to the direction of arrow Y by the action of the return spring 51 to thereby break the contacts and return the plunger 1 to its original position.

Thus, according to the present invention, a single piece of plate shape magnetic material is bent substantially in U shape and the respective ends of the top plate 18 and bottom plate 19 are further bent inwardly to form the second side plates 21 and 22, and substantially in the middle of said second side plates, further, the respective ends thereof are folded back outwardly to form a channel-like opening elongated in the direction in-which the plunger 1 slides, thereby to minimize magnetic loss between the yoke and the plunger. Further, the ends of the second side plates 21, 22 are joined together integrally at least at one side of the channel-like opening, so that a continuous magnetic pass is formed through the junction of the second side plates even the yoke is made of a single sheet of magnetic plate material, whereby magnetic loss between the yoke and the plunger can be minimized and also highly effective electromagnetic force can be obtained. Also, in the present invention, since an opening 25 is formed between the second side plates at the other side of the channel-like opening than said junction, the assembled unit of the coil and plunger can be easily incorporated into the yoke from one laterally opened side thereof. I

Further, since the buffer sheets 11, 12 made of nylon, polyester, flourine resin or the like are losely fitted on the respective faces of the lugs 23, 24 of the yoke, along which the plunger 1 is slided, as well as in the hollow space 8 ofthe coil bobbin 7, there is retained a suitable clearance between the yoke and the plunger,

thereby eliminating any noticeable variance in the attracting operation of the plunger 1 due to the remanence, and also, since these sheets are interposed between the plunger 1 and the coil bobbin 7, it is possible to minimize undesirable shaking due to the tolerance remained for the assembly work between the plunger and the coil bobbin, thus alleviating the problem of beat caused by such shaking of the plunger in the coil bobbin.

Conventionally, when the plunger 1 is attracted during the opening and closing operation, the end of the plunger may strike against the yoke to cause impact vibration of the electromagnet device, and as a reaction against said striking, there is also generated impact vibration in a direction opposite to the direction of movement of the plunger 1. This phenomenon continues for a certain period of time to give rise to a vibration of the yoke. This also causes a so-called chattering phenomenon to occur where the contacts are separated and contacted repeatedly, resulting in damage to the contacts.

According to the present invention, however, the buffer members formed from elastic masses of rubber, soft synthetic resin or the like are secured to both front and rear face portions on both sides of the first side plate of the yoke, so as to lessen impact between the plunger and the yoke by the presence of the cushion member at the rear face portion, while alleviating the reaction force produced in the plunger upon hitting the yoke by the cushion member at the front face portion, thereby reducing vibration of the electromagnet device. It is also possible to minimize chattering of the contacts due to the vibration of the plunger.

In a modified form of the buffer member, if a thick- -wall portion and thin-wall portion are provided, the

member may be selectively used depending on the magnitude of the impact force given.

It is also to be noted that, in the present invention,

1 the recesses 9 are formed in the flange 10 of the bobbin 6 and the cushion members 14 are partly fitted in said recessed, so that the cushion members will be prevented from being dislocated after the assembley.

Also, these cushion members are fitted into the lower case along the vertical slots in both side walls of the case, together with the electromagnet device, from the top opening of the case, so that they are securely fixed in position and will not be moved after once assembled.

' What is claimed is:

l. A small electromagnetic contactor comprising an insulating ease, fixed contact elements secured in said insulating case, movable contact elements opposed to said fixed contacts and supported resiliently by an actuator disposed slidably in said insulating case, an electromagnetic device comprising a generally U-shaped yoke having a narrowed opening at the open end of the U-shape, a coil bobbin contained and fixed in said yoke, a coil wound on said bobbin, and a plunger disposed coaxially in said bobbin so as to be slidable therein with its head end extending out of the yoke at said narrowed opening of the yoke, and means for operatively coupling said plunger to said actuator, said electromagnetic device and said coupling means being contained in said insulating case along with said contacts and said actuator, said yoke being formed of a single sheet of magnetic material which is bent to form said U-shape with the ends of the two legs at the open end of the U forming (l) a first pair of end sections bent toward each other to form said narrowed opening and further bent parallel to each other and to the direction of sliding movement of the plunger so as to provide guide walls for the plunger, (2) a second pair of end sections bent to butt against each other and welded together to form a magnetically closed circuit across the open end of the U for reducingmagnetic ted between longitudinal sliding faces of the plunger and inner surfaces of the coil bobbin surrounding the plunger.

3. An electromagnetic contactor according to claim 1, wherein said yoke is provided with cushion members on both sides of the yoke. 

1. A small electromagnetic contactor comprising an insulating case, fixed contact elements secured in said insulating case, movable contact elements opposed to said fixed contacts and supported resiliently by an actuator disposed slidably in said insulating case, an electromagnetic device comprising a generally U-shaped yoke having a narrowed opening at the open end of the Ushape, a coil bobbin contained and fixed in said yoke, a coil wound on said bobbin, and a plunger disposed coaxially in said bobbin so as to be slidable therein with its head end extending out of the yoke at said narrowed opening of the yoke, and means for operatively coupling said plunger to said actuator, said electromagnetic device and said coupling means being contained in said insulating case along with said contacts and said actuator, said yoke being formed of a single sheet of magnetic material which is bent to form said U-shape with the ends of the two legs at the open end of the U forming (1) a first pair of end sections bent toward each other to form said narrowed opening and further bent parallel to each other and to the direction of sliding movement of the plunger so as to provide guide walls for the plunger, (2) a second pair of end sections bent to butt against each other and welded together to form a magnetically closed circuit across the open end of the U for reducing magnetic losses from the yoke and (3) a pair of side sections bent parallel to each other and spaced farther apart from each other than said first end sections to form an opening communicating with the narrowed opening to provide a clearance for assembly of said coil, said coil bobbin, and said plunger within said yoke.
 2. A small electromagnetic contactor according to claim 1, in which at least a pair of buffer sheets are fitted between longitudinal sliding faces of the plunger and inner surfaces of the coil bobbin surrounding the plunger.
 3. An electromagnetic contactor according to claim 1, wherein said yoke is provided with cushion members on both sides of the yoke. 